Since I’m grounded for a bit due to software issues, I decided to take a few new photos of my VTOL build to share with others. I’ll add brief details among the photos for some aspects of the build that may have deviated from my initial plans.
Approximate weights (± 30 g using a hanging fishing scale) are as follows:
Dry 6.53 kg
Wet 10.33 kg (without multispectral camera)
MTOW 10.78 kg
Photo 1. Airframe pieces.
Photo 2. Airframe assembled.
Photo 3. Airspeed sensor Pitot tube.
Photo 4. Airspeed digital sensor board mounting.
I decided to nix the idea of using a PDB in the wings and just solder the power connections for the VTOL motors so I could save some weight.
Photo 5. VTOL power circuit wire junction inside wing.
The Mauch Power Cube has the option to use an external switch to control power to the board. This made things very convenient as I was testing different connections since I didn’t have to plug/unplug the Primary batteries each time I cycled power. The LED will be solid when the board is powered and blink intermittently when powered off but still has the batteries connected. I highly recommend considering the power switch if you use a Mauch Power Cube.
Photo 6. Switch for Primary system power board (Mauch power switch).
The soldering and routing of wires for the VTOL motors and ESC’s were a little tricky to sort out at first. After I had decided how I’d approach the problem everything went fine. On the first motor I soldered bullet connectors so that I could test spin direction on the bench. Afterwards, I resoldered the wires directly for the first and each subsequent CW and CCW motor accordingly. I had to cut out a little bit of foam in the Fighter shipping box so that there was space for the externally mounted ESC’s. I still stand by my earlier recommendation of going with the TMotor integrated arms to save you time and hassle during the assembly phase.
Photo 7. VTOL motor and ESC final external mounting.
The RC antennas used are made by Airbot and meant for the Herelink system. Their advantage over the stock Herelink antennas is that these are easily removable. They are mounted nearly perpendicular w.r.t. each other for signal coverage because they are omni-directional antennas. I went back and forth on whether to mount the FPV camera now or wait until later since it wasn’t an immediate necessity. I went for it and I decided to make a polycarbonate mount for the camera which was very simple to implement (vs. firing up the 3D printer). I used cold breaking/forming (bending) techniques and only had to attempt it once to get the right fit. This mount allows for adjustment to the camera pitch. Later I would like to remount with a servo so I can pan inflight…
Photo 8. FPV camera mount and radio antenna mounts.
The FPV system consists of the camera board and the analog-to-digital video converter. The converter is quite bulky in its case and after removing the plug connectors to save weight (thanks for the tip @GregCovey) the board is still wide but pretty thin. Everything fits nicely inside the recess in the front hatch cover. The camera board and converter get hot without air flow so I added a polycarbonate cover for protection and a 5V muffin fan. The fan pushes cabin air toward the hot boards and exhausts either through the holes in the polycarbonate or outside the airframe through the hatch penetration. This has worked great managing heat thus far with the Fighter sitting on the ground, hatches closed. I used some of the leftover MFE plastic anchor inserts to attach the cover.
Photo 9. FPV camera system in front hatch.
Photo 10. Front hatch internals.
Each power circuit (Primary, VTOL) uses a PDB as the main junction. I didn’t have the right epoxy/resin to “pot” the exposed contacts so I opted to sandwich the PDB’s between two pieces of polycarbonate. This provides protection, an attachment surface, creates an air gap between the foam frame and the exposed solder joints, and allows access to the PDB’s for future power modifications.
Photo 11. PDB for the Primary power system circuit.
Photo 12. Front hatch internals with Primary circuit batteries installed.
The Herelink Air unit gets hot without active air flow, even in open spaces.The unit fits well inside the RC hatch, however, it requires airflow so a 5V muffin fan was recessed into the hatch to be minimally invasive inside the compartment. The fan pulls in outside air for cooling.
Photo 13. Herelink Air RC unit mounting location.
Photo 14. Cargo hatch GPS mounting position.
Photo 15. Cargo hatch internals.
To support the weight of the VTOL system batteries I made a polycarbonate battery tray reinforced with carbon fiber spars laterally and then carbon fiber uprights. This helps to transfer the load to the central wing spars so the extra weight is not being held solely by the foam sides and bottom of the fuselage. The battery tray is removable as well as the rear carbon fiber uprights (note: rearward central wing spar is removable via a clever MFE design). Because the battery tray is removable it allows for a slung payload sensor (or another payload arrangement) in my next building phase.
Photo 16. Cargo hatch internals, battery tray and multispectral sensor mount.
Photo 17. Cargo hatch internals with VTOL circuit batteries installed.
Photo 18. Cargo hatch internals with multispectral camera mounted
Photo 19. Multispectral camera mount in belly of plane (rough fit)
Mounting the multispectral camera against the belly of the fuselage made it protrude further than I was comfortable with. I added a 1.5 cm thick, medium-density foam to help recess the camera and provide a secure, padded, compressive mount for the camera.
Photo 20. Multispectral camera mount in belly of plane with battery tray and foam padding offset.
Herelink ground unit/controller fits nicely in a small Pelican case.
Photo 21. Herelink Ground unit in transport case.
Bit of a firehose type of post, I partly apologize, but I’ve been busy in many things and haven’t been able to update progress!
Cheers,
Christian